The present invention relates, in general, to semiconductor devices, and more particularly, to optical semiconductor devices.
In the past, the semiconductor industry has utilized a variety of methods to implement optical semiconductor devices such as light emitting diodes. One previous method included forming multiple layers of semiconductor material on a gallium arsenide substrate and then creating a "T" shaped contact by etching the structure's top most layers. One such light emitting diode is described in U.S. Pat. No. 4,989,050 issued to Gaw et al on Jan. 29, 1991 which is hereby incorporated herein by reference.
One disadvantage with the previous method was inadvertent etching of the sides or edges of the "T" shaped contact's cross member. Generally, electrodes were formed by utilizing the cross member as a mask while depositing conductor material. The etching that affected the cross member's edges, altered the mask size thereby permitting the conductor material to create shorts across the diode's P-N junction and destroying the device.
Another disadvantage of previous methods was the number of processing steps required to form the "T" shaped contact. Generally the "T" shape was obtained by first etching layers off of the cross member. Then three successive etches were used to form the pedestal that supported the cross member thereby completing the "T" shape. These multiple etching operations resulted in a high manufacturing cost for the diode.
Accordingly, it is desirable to have a light emitting diode with a "T" shaped contact having a cross member whose sides or edges are not etched, with a P-N junction that is not shorted, and with a "T" shaped contact that is formed with a minimal number of processing steps.